Thyrotropin-releasing hormone-induced growth hormone secretion in dogs with primary hypothyroidism.
Domest Anim Endocrinol
; 34(2): 176-81, 2008 Feb.
Article
en En
| MEDLINE
| ID: mdl-17363208
Primary hypothyroidism in dogs is associated with increased release of growth hormone (GH). In search for an explanation we investigated the effect of intravenous administration of thyrotropin-releasing hormone (TRH, 10 microg/kg body weight) on GH release in 10 dogs with primary hypothyroidism and 6 healthy control dogs. The hypothyroid dogs had a medical history and physical changes compatible with hypothyroidism and were included in the study on the basis of the following criteria: plasma thyroxine concentration < 2 nmol/l and plasma thyrotropin (TSH) concentration > 1 microg/l. In addition, (99m)TcO(4)(-) uptake during thyroid scintigraphy was low or absent. TRH administration caused plasma TSH concentrations to rise significantly in the control dogs, but not in the hypothyroid dogs. In the dogs with primary hypothyroidism, the mean basal plasma GH concentration was relatively high (2.3+/-0.5 microg/l) and increased significantly (P=0.001) 10 and 20 min after injection of TRH (to 11.9+/-3.5 and 9.8+/-2.7 microg/l, respectively). In the control dogs, the mean basal plasma GH concentration was 1.3+/-0.1 microg/l and did not increase significantly after TRH administration. We conclude that, in contrast to healthy control dogs, primary hypothyroid dogs respond to TRH administration with a significant increase in the plasma GH concentration, possibly as a result of transdifferentiation of somatotropic pituitary cells to thyrosomatotropes.
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Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Hormona Liberadora de Tirotropina
/
Hormona de Crecimiento Humana
/
Enfermedades de los Perros
/
Hipotiroidismo
Límite:
Animals
Idioma:
En
Revista:
Domest Anim Endocrinol
Asunto de la revista:
ENDOCRINOLOGIA
/
MEDICINA VETERINARIA
Año:
2008
Tipo del documento:
Article
País de afiliación:
Países Bajos
Pais de publicación:
Estados Unidos